Keyboard type electronic musical instrument

ABSTRACT

A keyboard type electronic musical instrument, having a group of twelve keys per octave for playing the even tempered scale, is adapted to sound the quarter tone between two notes of the even tempered scale when the keys corresponding to said two notes are simultaneously operated. The instrument employs a voltage controlled oscillator, a voltage source having output voltages proportional to the frequencies of the notes of the scale, a group of key operated switches and series resistors for selectively connecting the oscillator to the voltage source. The resistors of operated switches form a voltage divider when two keys are simultaneously operated and a voltage equal to the average of the converted voltages is applied to the oscillator to produce the intermediate tone.

United States Patent 1191 1111 3,786,166 Mieda 1 Jan. 15, 1974 [5 1 KEYBOARD TYPE ELECTRONIC MUSICAL 3,288,904 11/1966 George 84/].01

INSTRUMENT 3,538,804 11/1970 George 84/1.01

[75] Inventor: Fumio Mieda, Saitama, Japan [73] Assignee: Keio Giken Kogiyo Kabushikikaishiya, Tokyo, Japan [22] Filed: May 19, 1972 [21] Appl. No.: 255,299

Related U.S. Application Data [63] Continuation of Ser. No. 121,831, March 8, 1971,

abandoned.

[52] U.S. Cl 84/1.01, 84/124, 84/DIG. 2O [51] Int. Cl. ..G10h 1/02 [58] Field of Search 84/1'.01,1.11,1.17, 84/1.19,, 1.24, DIG. 2, DIG. 20, DIG. 23

[56] References Cited UNITED STATES PATENTS 2,933,699 4/1960 Bonham 84/DIG. 20 3,283,057 11/1966 Campbell 3,511,917 5/1970 Mallett .1 3,665,089 5/1972 Stcarns .1 84/].01 2,710,555 6/1955 Martin 84/101 Primary Examiner-Richard B. Wilkinson Assistant Examiner-Stanley J. Witkowski Attorney-Marshall & Yeasting [57] ABSTRACT A keyboard type electronic musical instrument, having a group of twelve keys per octave for playing the even tempered scale, is adapted to sound the quarter tone between two notes of the even tempered scale when the keys corresponding to said two notes are simultaneously operated. The instrument employs a voltage controlled oscillator, a voltage source having output voltages proportional to the frequencies of the notes of the scale, a group of key operated switches and series resistors for selectively connecting the oscillator to the voltage source. The resistors of operated switches form a voltage divider when two keys are simultaneously operated and a voltage equal to the average of the converted voltages is applied to the oscillator to produce the intermediate tone.

2 Claims, 2 Drawing Figures Voltage- Controlled Amplifier Speaker Oscil lotor- KEYBOARD TYPE ELECTRONIC MUSICAL INSTRUMENT This is a continuation of application, Ser. No. 121,831, filed Mar. 8, 1971, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a keyboard type electronic musical instrument which is provided with a plurality of keys and adapted to provide a predetermined musical scale by sequential depression of the keys and the invention is of particular utility when employed in such a keyboard type electronic musical instrument designed to provide the dodecaphonic scale.

2. Description of the Prior Art With conventional electronic musical instruments of the type above mentioned, semitones can be produced but quarter tones cannot be produced. Therefore, the prior art electronic musical instruments cannot raise the performance effect such as those obtainable with, for example, a guitar, a saxophone, a clarinet and the like.

SUMMARY OF THE INVENTION I Accordingly, the present invention has for its object to provide a keyboard type electronic musical instrument which is designed to produce quarter tones without requiring any special keys therefor. In accordance with this invention a quarter tone can be produced by simultaneous depression of two adjacent keys.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a system diagram showingone example of a keyboard type electronic musical instrument of this invention; and

FIG. 2 is a graph showing a voltage-frequency characteristic, for explaining the operation of the keyboard type musical instrument examplied in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 reference numeral 1 indicates generally one portion of a usual dodecaphonic keyboard, which is shown to consist of keys K, to K of one octave for the sake of brevity and are arranged in order of C,"

"(i (1)") D," as usual.

Reference numeral-2 designates generally a switch array which is provided corresponding to the keyboard 1 and includes switches S, to 8, respectively associated with the keys K, to 14, and closed by the depression of the respective keys K, to K,,.

Reference numeral 3 identifies a DC power source circuit. in which resistors R, to R,, are respectively connected in series to a power source 4 through a resistor R,, to derive DC voltages V, to V,, at connection points P, to P,., between adjacent resistors respectively. The connection points P, to P,,, are respectively conneeted to the switches S, to 8,, through resistors r, to r,. of the same relatively high resistance value.

Reterncce numeral 5 indicates a voltage-controlled oscillator adapted to produce a tone signal ofa fundamental frequency corresponding to an input voltage. The oscillator 5 is connected at input side to the other ends of the switches S, to S,, and connected at output side to a speaker system 7 through an amplifier 6.

With such an arrangement as above described, depression of the keys K, to K, respectively applies the voltages V, to V to the voltage controlled oscillator 5 to derive therefrom tone signals of fundamental frequenciesf to f ,2 Corresponding to the voltages and the resulting tone signals are supplied through the amplifier 6 to the speaker 7 to be thereby reproduced.

Accordingly, if the values of the resistors R to R in the power source circuit 3 and consequently the values of the voltages V, to V are selected so that the fundamental frequeneies f, f may respectively be equal to those of 0, O (D*),D forming the dodecaphonic musical scale, the relationships of the voltages V,, V with the frequenciesfi, are such as shown in FIG. 2, in which the values of the voltages V,, V become sequentially higher in their order to provide the frequencies f,, f,,, corresponding thereto. Therefore, selective depression of any one of the keys K, to K produces a particular semitone of the fundamental frequency of the depressed key, thus achieving keyboard performance in the same manner as that of a usual keyboard type monotony electronic musical instrument.

However, when the keys for example, K, and K are simultaneously depressed, the voltage-controlled oscillator 5 is supplied with a voltage which is substantially one halfof the sum of the voltages V, and V, or (V, V )/2 so that a tone signal of a fundamcmtal frequency about (f, +f )/2 is produced by the oscillator 5. Since the frequencicsf, and f,, are equal to those of C and C (1)") simultaneous depression of the keys K, and K provides a quarter tone which is intermediate between those of C and C (1)"). Further, simultaneous depression of thekeys, for example, K, and K similarly produce a quarter tone between C and ELD.I1 I

The followin will describe concrete numerical values of the circuit elements of this invention.

The voltage-controlled oscillator 5 is an oscillator which has a linear voltage-frequency characteristic and produces a frequency e/s when supplied with 1 volt. The power source 4 of the power source circuit 3 has a voltage of 4.9388 volts. The resistance values of the resistors R to R,, are as follows:

: 2616.3 ohms 155.5 ohms 164.8 ohms 174.7 ohms 185.0 ohms 196.0 ohms 207.6 ohms 220.1 ohms 233.0 ohms 247.0 ohms R10: .6 Ohms R,,: 277.2 ohms R12: 0 Ohms The resistance values of the resistors r, to m, are re= spectively 10 kiloohms.

With such resistance values of the resistors R to R a current of 1 mA flows from the power source 4 to the series circuit ofthe resistors R, to R,,, thereby to derive the following voltages V, to V,, at the connection points P, to P,,,. I

V,: 2.6163 volts V 2.7718 volts V 2.9366 volts V 3.1113 volts V,:3.2963 volts V 3.4923 volts V 3.6999 volts V 3.9200 volts V 4.1530 volts V 4.4000 volts V 4.6616 volts V 4.9388 volts Since the resistance values of the resistors r to r are large compared to the resistance of the resistors R to R so that when each of the switches S to 5, is closed each of the aforementioned voltages is supplied to the voltage-controlled oscillator 5. Accordingly, depression of each of the keys K to K derives each of the following fundamental frequencies from the oscillator 5.

261.63 c/s 277.18 c/s 293.66 c/s 311.13 0/5 329.63 c/s 349.23 e/s 369.99 cs/s 392.00 e/s 415.30 c/s K 440.00 e/s K 466.16 c/s K 493.88 c/s These fundamental frequencies correspond to those of C". C (-D D. of the dodecaphonic scale.

Further, when the switches, for example, S and S are concurrently closed, a voltage, which is substantially (V Va)/2 (2.7718 2.9366 V)/2, is applied to the voltage-controlled oscillator 5. As a result ofthis, the oscillator produces a frequency 285.42 c/s corresponding to a quarter tone which is intermediate between C and D."

With the present invention, a quarter tone can be produced by simultaneous depression of adjacent keys without requiring any special keys therefor. Therefore, this invention provides a keyboard type electronic musical instrument of high performance effect.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

1 claim as my invention 1. In a keyboard electronic musical instrument comprising a keyboard provided with at least one group of twelve keys for one octave, in combination, an electrical power source having a plurality of output points delivering a plurality of output voltages proportional to the frequencies of the tones corresponding to said keys, a switch for each key operated by the key, a resistor connected in series with each switch, the resistances of said resistors being substantially equal to each other and large compared to the impedance of the power source and a voltage controlled oscillator having a control voltage input terminal, each switch and series connected resistor being separately connected between said control voltage input terminal and the power source terminal corresponding to the switch and asso ciated key, whereby actuation of the keys individually applies corresponding voltages to the voltage controlled oscillator and simultaneous actuation of two keys applies a voltage intermediate the voltages of the switch connected points to thevoltage controlled oscillator.

2. A circuit for a keyboard type electronic musical instrument according to claim 1 in which said power source includes a plurality of resistors connected in series with the junctions between the resistors connected to said output points. 

1. In a keyboard electronic musical instrument comprising a keyboard provided with at least one group of twelve keys for one octave, in combination, an electrical power source having a plurality of output points delivering a plurality of output voltages proportional to the frequencies of the tones corresponding to said keys, a switch for each key operated by the key, a resistor connected in series with each switch, the resistances of said resistors being substantially equal to each other and large compared to the impedance of the power source and a voltage controlled oscillator having a control voltage input terminal, each switch and series connected resistor being separately connected between said control voltage input terminal and the power source terminal corresponding to the switch and associated key, whereby actuation of the keys individually applies corresponding voltages to the voltage controlled oscillator and simultaneous actuation of two keys applies a voltage intermediate the voltages of the switch connected points to the voltage controlled oscillator.
 2. A circuit for a keyboard type electronic musical instrument according to claim 1 in which said power source includes a plurality of resistors connected in series with the junctions between the resistors connected to said output points. 